Doctoral theses
Current Record: 193 of 229
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| Identifier |
000033706 |
| Title |
Μηχανισμός των (4+2) Κυκλοπροσθηκών και αντιδράσεων "Ενίου" του φουλερενίου C60 με Αλκένια. Αυτοοξειδώσεις παραγώγων του C60 με οξυγόνο απλής κατάστασης(1Ο2) |
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Author
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Χρονάκης, Νικόλαος Ε.
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Thesis advisor
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Ορφανόπουλος, Μιχαήλ
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| Abstract |
This dissertation describes certain reaction mechanisms of fullerene C60 chemistry. The principle findings are as follows: In the First Chapter, the mechanism of ene reaction of C60 with arylallyl alkenes was investigated. For this purpose, primary isotope effects were measured. Additionally, the rate constant in solvents of different polarity and the ρ value of Hammett equation were determined. The results are in agreement with a concerted mechanism or the reversible formation of a charged or dipolar intermediate, followed by the C-H(D) bond cleavage in the rate-limiting step. In the Second Chapter, the mechanism of the [4+2] cycloaddition of conjugated dienes to C60 was studied. The stereochemistry of the Diels-Alder reaction of trans,trans and cis,trans-2,4-hexadiene is in agreement with a concerted mechanism. Additionally, isomerization of cis,trans to trans,trans-2,4-hexadiene took place through electron transfer from diene to the ground state of C60. Secondly, α-secondary isotope effects were measured in the Diels-Alder reaction of rigid s-cis dienes to C60. The inverse isotope effects support a concerted mechanism that occurs via a symmetrical transition state. Eventually, α and β-secondary isotope effects were determined in [4+2] cycloaddition of anthracene to C60. The inverse α-secondary isotope effect in conjuction with the unity value of β-secondary isotope effect are consistent with a synchronous mechanism. In the Third Chapter, the synthesis of 1,2-RC60H derivatives and the regioselectivity of their self-oxidation reactions are discussed. 1,2-RC60H derivatives are prepared through electron transfer from C602- to allyl bromides followed by protonation of the intermediate RC60-. RC60H derivatives sensitize singlet oxygen formation followed by regiospecific allylic hydrogen abstraction from the site near to the bulkier C60 group.
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| Language |
Greek |
| Issue date |
2000-09-01 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
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Type of Work--Doctoral theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/8/7/9/metadata-dlib-2000DIS0907.tkl
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| Views |
328 |
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